File:Aveiro March 2012-13.jpg|thumb|right|275px|The lighthouse of Aveiro Light|Aveiro, west coast of Portugal
File:Roman Rock Lighthouse.webm|thumbnail|Aerial drone footage of the Roman Rock Lighthouse off the southern coast of South Africa.
A '''lighthouse''' is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses, and to serve as a navigational aid
for maritime pilot
s at sea or on inland waterways.
Lighthouses mark dangerous coastlines, hazardous shoal
s, and safe entries to harbors, and can assist in aerial navigation. Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and use of electronic navigational systems.